hw/virtio-console.c

   1 /*
   2  * Virtio Console Device
   3  *
   4  * Copyright IBM, Corp. 2008
   5  *
   6  * Authors:
   7  *  Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #include "hw.h"
  15 #include "qemu-char.h"
  16 #include "virtio.h"
  17 #include "virtio-console.h"
  18
  19
  20 typedef struct VirtIOConsole
  21 {
  22     VirtIODevice vdev;
  23     VirtQueue *ivq, *ovq;
  24     CharDriverState *chr;
  25 } VirtIOConsole;
  26
  27 static VirtIOConsole *to_virtio_console(VirtIODevice *vdev)
  28 {
  29     return (VirtIOConsole *)vdev;
  30 }
  31
  32 static void virtio_console_handle_output(VirtIODevice *vdev, VirtQueue *vq)
  33 {
  34     VirtIOConsole *s = to_virtio_console(vdev);
  35     VirtQueueElement elem;
  36
  37     while (virtqueue_pop(vq, &elem)) {
  38         ssize_t len = 0;
  39         int d;
  40
  41         for (d = 0; d < elem.out_num; d++) {
  42             len += qemu_chr_write(s->chr, (uint8_t *)elem.out_sg[d].iov_base,
  43                                   elem.out_sg[d].iov_len);
  44         }
  45         virtqueue_push(vq, &elem, len);
  46         virtio_notify(vdev, vq);
  47     }
  48 }
  49
  50 static void virtio_console_handle_input(VirtIODevice *vdev, VirtQueue *vq)
  51 {
  52 }
  53
  54 static uint32_t virtio_console_get_features(VirtIODevice *vdev)
  55 {
  56     return 0;
  57 }
  58
  59 static int vcon_can_read(void *opaque)
  60 {
  61     VirtIOConsole *s = (VirtIOConsole *) opaque;
  62
  63     if (!virtio_queue_ready(s->ivq) ||
  64         !(s->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK) ||
  65         virtio_queue_empty(s->ivq))
  66         return 0;
  67
  68     /* current implementations have a page sized buffer.
  69      * We fall back to a one byte per read if there is not enough room.
  70      * It would be cool to have a function that returns the available byte
  71      * instead of checking for a limit */
  72     if (virtqueue_avail_bytes(s->ivq, TARGET_PAGE_SIZE, 0))
  73         return TARGET_PAGE_SIZE;
  74     if (virtqueue_avail_bytes(s->ivq, 1, 0))
  75         return 1;
  76     return 0;
  77 }
  78
  79 static void vcon_read(void *opaque, const uint8_t *buf, int size)
  80 {
  81     VirtIOConsole *s = (VirtIOConsole *) opaque;
  82     VirtQueueElement elem;
  83     int offset = 0;
  84
  85     /* The current kernel implementation has only one outstanding input
  86      * buffer of PAGE_SIZE. Nevertheless, this function is prepared to
  87      * handle multiple buffers with multiple sg element for input */
  88     while (offset < size) {
  89         int i = 0;
  90         if (!virtqueue_pop(s->ivq, &elem))
  91                 break;
  92         while (offset < size && i < elem.in_num) {
  93             int len = MIN(elem.in_sg[i].iov_len, size - offset);
  94             memcpy(elem.in_sg[i].iov_base, buf + offset, len);
  95             offset += len;
  96             i++;
  97         }
  98         virtqueue_push(s->ivq, &elem, size);
  99     }
 100     virtio_notify(&s->vdev, s->ivq);
 101 }
 102
 103 static void vcon_event(void *opaque, int event)
 104 {
 105     /* we will ignore any event for the time being */
 106 }
 107
 108 static void virtio_console_save(QEMUFile *f, void *opaque)
 109 {
 110     VirtIOConsole *s = opaque;
 111
 112     virtio_save(&s->vdev, f);
 113 }
 114
 115 static int virtio_console_load(QEMUFile *f, void *opaque, int version_id)
 116 {
 117     VirtIOConsole *s = opaque;
 118
 119     if (version_id != 1)
 120         return -EINVAL;
 121
 122     virtio_load(&s->vdev, f);
 123     return 0;
 124 }
 125
 126 VirtIODevice *virtio_console_init(DeviceState *dev)
 127 {
 128     VirtIOConsole *s;
 129     s = (VirtIOConsole *)virtio_common_init("virtio-console",
 130                                             VIRTIO_ID_CONSOLE,
 131                                             0, sizeof(VirtIOConsole));
 132     if (s == NULL)
 133         return NULL;
 134
 135     s->vdev.get_features = virtio_console_get_features;
 136
 137     s->ivq = virtio_add_queue(&s->vdev, 128, virtio_console_handle_input);
 138     s->ovq = virtio_add_queue(&s->vdev, 128, virtio_console_handle_output);
 139
 140     s->chr = qdev_init_chardev(dev);
 141     qemu_chr_add_handlers(s->chr, vcon_can_read, vcon_read, vcon_event, s);
 142
 143     register_savevm("virtio-console", -1, 1, virtio_console_save, virtio_console_load, s);
 144
 145     return &s->vdev;
 146 }